Mucorales and Mucormycosis: Recent Insights and Future Prospects

Comprehensive Review on the Virulence Factors and Therapeutic Strategies with the Aid of Artificial Intelligence against Mucormycosis

Mucormycosis, a rare but deadly fungal infection, was an epidemic during the COVID-19 pandemic. The rise in cases (COVID-19-associated mucormycosis, CAM) is attributed to excessive steroid and antibiotic use, poor hospital hygiene, and crowded settings. Major contributing factors include diabetes and weakened immune systems. The main manifesting forms of CAM─cutaneous, pulmonary, and the deadliest, rhinocerebral─and disseminated infections elevated mortality rates to 85%. Recent focus lies on small-molecule inhibitors due to their advantages over standard treatments like surgery and liposomal amphotericin B (which carry several long-term adverse effects), offering potential central nervous system penetration, diverse targets, and simpler dosing owing to their small size, rendering the ability to traverse the blood-brain barrier via passive diffusion facilitated by the phospholipid membrane. Adaptation and versatility in mucormycosis are facilitated by a multitude of virulence factors, enabling the pathogen to dynamically respond to various environmental stressors. A comprehensive understanding of these virulence mechanisms is imperative for devising effective therapeutic interventions against this highly opportunistic pathogen that thrives in immunocompromised individuals through its angio-invasive nature. Hence, this Review delineates the principal virulence factors of mucormycosis, the mechanisms it employs to persist in challenging host environments, and the current progress in developing small-molecule inhibitors against them.

The utility of Drosophila melanogaster as a fungal infection model

Invasive fungal diseases have profound effects upon human health and are on increase globally. The World Health Organization (WHO) in 2022 published the fungal priority list calling for improved public health interventions and advance research. Drosophila melanogaster presents an excellent model system to dissect host-pathogen interactions and has been proved valuable to study immunopathogenesis of fungal diseases. In this review we highlight the recent advances in fungal-Drosophila interplay with an emphasis on the recently published WHO's fungal priority list and we focus on available tools and technologies.

First insights on the susceptibility of native coccidicidal fungi Mucor circinelloides and Mucor lusitanicus to different avian antiparasitic drugs

BACKGROUND

The combined application of predatory fungi and antiparasitic drugs is a sustainable approach for the integrated control of animal gastrointestinal (GI) parasites. However, literature addressing the possible interference of antiparasitic drugs on the performance of these fungi is still scarce. This research aimed to assess the in vitro susceptibility of six native coccidicidal fungi isolates of the species Mucor circinelloides and one Mucor lusitanicus isolate to several antiparasitic drugs commonly used to treat GI parasites' infections in birds, namely anthelminthics such as Albendazole, Fenbendazole, Levamisole and Ivermectin, and anticoccidials such as Lasalocid, Amprolium and Toltrazuril (drug concentrations of 0.0078-4 µg/mL), using 96-well microplates filled with RPMI 1640 medium, and also on Sabouraud Agar (SA).

RESULTS

This research revealed that the exposition of all Mucor isolates to the tested anthelminthic and anticoccidial drug concentrations did not inhibit their growth. Fungal growth was recorded in RPMI medium, after 48 h of drug exposure, as well as on SA medium after exposure to the maximum drug concentration.

CONCLUSIONS

Preliminary findings from this research suggest the potential compatibility of these Mucor isolates with antiparasitic drugs for the integrated control of avian intestinal parasites. However, further in vitro and in vivo studies are needed to confirm this hypothesis.

Trans-kingdom fungal pathogens infecting both plants and humans, and the problem of azole fungicide resistance

Azole antifungals are abundantly used in the environment and play an important role in managing fungal diseases in clinics. Due to the widespread use, azole resistance is an emerging global problem for all applications in several fungal species, including trans-kingdom pathogens, capable of infecting plants and humans. Azoles used in agriculture and clinics share the mode of action and facilitating cross-resistance development. The extensive use of azoles in the environment, e.g., for plant protection and wood preservation, contributes to the spread of resistant populations and challenges using these antifungals in medical treatments. The target of azoles is the cytochrome p450 lanosterol 14-α demethylase encoded by the CYP51 (called also as ERG11 in the case of yeasts) gene. Resistance mechanisms involve mainly the mutations in the coding region in the CYP51 gene, resulting in the inadequate binding of azoles to the encoded Cyp51 protein, or mutations in the promoter region causing overexpression of the protein. The World Health Organization (WHO) has issued the first fungal priority pathogens list (FPPL) to raise awareness of the risk of fungal infections and the increasingly rapid spread of antifungal resistance. Here, we review the main issues about the azole antifungal resistance of trans-kingdom pathogenic fungi with the ability to cause serious human infections and included in the WHO FPPL. Methods for the identification of these species and detection of resistance are summarized, highlighting the importance of these issues to apply the proper treatment.

COVID-19 associated mucormycosis surge: A review on multi-pathway mechanisms

Mucormycosis is a fungal infection caused by moulds from the Mucorales order. Concerns have been mounting due to the alarming increase in severe morbidity and mortality associated with mucormycosis during the COVID-19 pandemic. This condition, known as COVID-19-associated mucormycosis (CAM), has been linked to various environmental, host-related, and medical factors on a global scale. We have categorized the most significant potential risk factors for developing mucormycosis in individuals with a previous history of coronavirus infection into 10 major categories. These categories include acute hyperglycemia, the impact of cytokine release, immune response deficiencies in COVID-19 patients, microvasculopathy and dysfunction of endothelial cells, imbalances in iron metabolism, metabolic acidosis, organ damage resulting from COVID-19, underlying health conditions (such as diabetes), environmental factors, and medical treatments that can be iatrogenic in nature (such as inappropriate glucocorticoid use). Many of these factors can lead to potentially life-threatening infections that can complicate the treatment of COVID-19. Physicians should be vigilant about these factors because early detection of mucormycosis is crucial for effective management of this condition.

Mucormycosis: update on clinical presentation, diagnosis, and treatment

PURPOSE OF REVIEW

Mucormycosis (MCR) is a common opportunistic mold infection, and Mucorales were recently designated by WHO as priority pathogens. The interest in this infection has risen significantly since the major outbreak of MCR in the context of the COVID-19 pandemic, particularly in India. Herein, we summarize recently (last 24 months) published information regarding clinical aspects of MCR.

RECENT FINDINGS

The disease remains protean in its clinical presentation, difficult to diagnose, and challenging to treat. In 2021, cases of COVID-19-associated mucormycosis (CAM) exploded in India during COVID-19 and manifested primarily as sino-orbital or sino-cerebral disease. Its classic risk factors included the triad of COVID-19, uncontrolled diabetes mellitus and use of corticosteroids. Despite difficulties in the timely diagnosis of MCR, significant progress has been made with the use of molecular techniques in blood to assist with earlier diagnosis, which can facilitate earlier appropriate therapy and improve outcomes. In addition, advances have been made in the use of imaging to stage the disease, determining what types of multimodal therapy are required depending on staging, and tissue-based identification of Mucorales.

SUMMARY

Although the outlook for MCR has improved, effective new antifungals, risk stratification, and the optimal multimodality approaches remain an unmet need.

The Mechanism of Transcription Factor Swi6 in Regulating Growth and Pathogenicity of Ceratocystis fimbriata: Insights from Non-Targeted Metabolomics

Ceratocystis fimbriata (C. fimbriata) is a notorious pathogenic fungus that causes sweet potato black rot disease. The APSES transcription factor Swi6 in fungi is located downstream of the cell wall integrity (CWI)-mitogen-activated protein kinase (MAPK) signaling pathway and has been identified to be involved in cell wall integrity and virulence in several filamentous pathogenic fungi. However, the specific mechanisms by which Swi6 regulates the growth and pathogenicity of plant pathogenic fungi remain elusive. In this study, the SWI6 deletion mutants and complemented strains of C. fimbriata were generated. Deletion of Swi6 in C. fimbriata resulted in aberrant growth patterns. Pathogenicity assays on sweet potato storage roots revealed a significant decrease in virulence in the mutant. Non-targeted metabolomic analysis using LC-MS identified a total of 692 potential differentially accumulated metabolites (PDAMs) in the ∆Cfswi6 mutant compared to the wild type, and the results of KEGG enrichment analysis demonstrated significant enrichment of PDAMs within various metabolic pathways, including amino acid metabolism, lipid metabolism, nucleotide metabolism, GPI-anchored protein synthesis, and ABC transporter metabolism. These metabolic pathways were believed to play a crucial role in mediating the growth and pathogenicity of C. fimbriata through the regulation of CWI. Firstly, the deletion of the SWI6 gene led to abnormal amino acid and lipid metabolism, potentially exacerbating energy storage imbalance. Secondly, significant enrichment of metabolites related to GPI-anchored protein biosynthesis implied compromised cell wall integrity. Lastly, disruption of ABC transport protein metabolism may hinder intracellular transmembrane transport. Importantly, this study represents the first investigation into the potential regulatory mechanisms of SWI6 in plant filamentous pathogenic fungi from a metabolic perspective. The findings provide novel insights into the role of SWI6 in the growth and virulence of C. fimbriata, highlighting its potential as a target for controlling this pathogen.

Fungal taxonomy: A puzzle with many missing pieces

Fungi are multifaceted organisms found in almost all ecosystems on Earth, where they establish various types of symbiosis with other living beings. Despite being recognized by humans since ancient times, and the high number of works delving into their biology and ecology, much is still unknown about these organisms. Some criteria classically used for their study are nowadays limited, generating confusion in categorizing them, and even more, when trying to understand their genealogical relationships. To identify species within Fungi, phenotypic characters to date are not sufficient, and to construct a broad phylogeny or a phylogeny of a particular group, there are still gaps affecting the generated trees, making them unstable and easily debated. For health professionals, fungal identification at lower levels such as genus and species, is enough to select the most appropriate therapy for their control, understand the epidemiology of clinical pictures associated, and recognize outbreaks and antimicrobial resistance. However, the taxonomic location within the kingdom, information with apparently little relevance, can allow phylogenetic relationships to be established between fungal taxa, facilitating the understanding of their biology, distribution in nature, and pathogenic potential evolution. Advances in molecular biology and computer science techniques from the last 30 years have led to crucial changes aiming to establish the criteria to define a fungal species, allowing us to reach a kind of stable phylogenetic construction. However, there is still a long way to go, and it requires the joint work of the scientific community at a global level and support for basic research.

COVID-19 and Mucormycosis of Orofacial Region: A Scoping Review

During the second wave of coronavirus disease, or COVID-19, infection due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus in the year 2021 around the globe, there is a surge in the number of cases of mucormycosis or "Black Fungus" that is directly/indirectly associated with COVID-19. In this review article, mucormycosis of the orofacial region has gained importance from the maximum published literature (45 articles) from various databases like PubMed, Google Scholar, Scopus, Web of Science, and Embase. Rhino-orbital cerebral mucormycosis (ROCM) is a fatal condition associated with COVID-19 among categories of mucormycosis such as pulmonary, oral, gastrointestinal, cutaneous, and disseminated. ROCM targets the maxillary sinus, also involving teeth of the maxilla, orbits, and ethmoidal sinus. These are of particular interest to dentists and oral pathologists for proper diagnosis and identification. Co-morbid conditions, especially diabetes mellitus type II, have to be monitored carefully in COVID-19 patients as they have a higher risk of developing mucormycosis. In this review article, various presentations of COVID-19-linked mucormycosis are mentioned having particular emphasis on pathogenesis, signs and symptoms, clinical presentation, various diagnostic modalities including histopathology, radiology like CT and MRI, serology, tissue culture, various laboratory investigations, treatment protocols, management with prognosis, and so on. Any suspected case of mucormycosis needs quick detection and treatment since it progresses quickly due to the destructive course of infection. Long-term follow-up along with proper care is a must to detect any kind of recurrence.